When “fullscreening” the canvas on a secondary screen, there is some space at the top left transparent (where the mac menu bar usually is).

The full screen control changed in Mac OS X Mavericks, and the new method is not yet supported by easyDCP Player.

As a workaround, deselect the option "Displays have separate spaces" in the Mission Control pane of System Preferences. A Logout is required for the changes to take effect.